St. John's Wort Interactions Overview

Additional Details

Is St. John's Wort Safe? Are There Any Warnings?

St. John's Wort is generally considered safe when taken orally and used appropriately. Studies suggest that doses of up to 900 mg daily for up to 12 weeks are safe. There is also evidence supporting its safe use for over a year. In fact, it may have better tolerability compared to other antidepressant medications. However, large doses of St. John's Wort extract can be potentially unsafe due to the risk of severe skin reactions when exposed to sunlight. Pregnant women should avoid taking St. John's Wort due to the potential risk of birth defects. It's important to note that more research is needed in this area.

How Is St. John's Wort Thought to Work? What Is the Mechanism of Action?

The active components of St. John's Wort, such as hyperforin and hypericin, interact with various neurotransmitters in the brain, including serotonin, dopamine, and norepinephrine. These interactions may help regulate mood and emotions. St. John's Wort may also inhibit the reuptake of these neurotransmitters, increasing their availability in the brain. Additionally, it acts as an antagonist at certain receptors and influences the release and uptake of other neurotransmitters like GABA and glutamate. These mechanisms are believed to contribute to the antidepressant effects of St. John's Wort.

Pharmacokinetics

Absorption: When St. John's Wort is taken orally, it is absorbed into the bloodstream. Steady-state plasma concentrations are reached within a few days of regular use. The maximum plasma levels of the active components, hypericin, and pseudohypericin, depend on the dosage administered.

Distribution: St. John's Wort components can be found in the serum and other bodily fluids, with higher concentrations observed in the serum compared to the skin blister fluid.

Metabolism: The liver metabolizes hyperforin, producing several metabolites through the hydroxylation pathway.

Elimination: The half-life of elimination varies for different components of St. John's Wort, ranging from 9 to 36 hours. The active constituents are eventually eliminated from the body through various processes.

Interaction Overview (See Below for Full List)

St. John's Wort can interact with other medications and substances, affecting their effectiveness or causing adverse effects. It can induce the metabolism of certain drugs, reducing their concentration in the bloodstream. This can be problematic when taking medications that require consistent blood levels for therapeutic effects. It's important to consult with a healthcare professional before combining St. John's Wort with other medications.

Common Side Effects to Watch For

When taken orally, common side effects of St. John's Wort may include diarrhea, dizziness, dry mouth, gastrointestinal discomfort, fatigue, headache, insomnia, restlessness, and sedation. When used topically, it may cause skin rash and increased sensitivity to sunlight, known as photodermatitis.

Are Supplements Standardized?

Yes, various St. John's Wort preparations used in clinical research are standardized to ensure consistent content of active components. The standardization is usually based on the concentration of hypericin or hyperforin. Different products may have varying standardizations, and some may also include additional ingredients in combination with St. John's Wort.

Is St. John's Wort Safe? Are There Any Warnings?

St. John's Wort is generally considered safe when taken orally and used appropriately. Studies suggest that doses of up to 900 mg daily for up to 12 weeks are safe. There is also evidence supporting its safe use for over a year. In fact, it may have better tolerability compared to other antidepressant medications. However, large doses of St. John's Wort extract can be potentially unsafe due to the risk of severe skin reactions when exposed to sunlight. Pregnant women should avoid taking St. John's Wort due to the potential risk of birth defects. It's important to note that more research is needed in this area.

How Is St. John's Wort Thought to Work? What Is the Mechanism of Action?

The active components of St. John's Wort, such as hyperforin and hypericin, interact with various neurotransmitters in the brain, including serotonin, dopamine, and norepinephrine. These interactions may help regulate mood and emotions. St. John's Wort may also inhibit the reuptake of these neurotransmitters, increasing their availability in the brain. Additionally, it acts as an antagonist at certain receptors and influences the release and uptake of other neurotransmitters like GABA and glutamate. These mechanisms are believed to contribute to the antidepressant effects of St. John's Wort.

Pharmacokinetics

Absorption: When St. John's Wort is taken orally, it is absorbed into the bloodstream. Steady-state plasma concentrations are reached within a few days of regular use. The maximum plasma levels of the active components, hypericin, and pseudohypericin, depend on the dosage administered.

Distribution: St. John's Wort components can be found in the serum and other bodily fluids, with higher concentrations observed in the serum compared to the skin blister fluid.

Metabolism: The liver metabolizes hyperforin, producing several metabolites through the hydroxylation pathway.

Elimination: The half-life of elimination varies for different components of St. John's Wort, ranging from 9 to 36 hours. The active constituents are eventually eliminated from the body through various processes.

Interaction Overview (See Below for Full List)

St. John's Wort can interact with other medications and substances, affecting their effectiveness or causing adverse effects. It can induce the metabolism of certain drugs, reducing their concentration in the bloodstream. This can be problematic when taking medications that require consistent blood levels for therapeutic effects. It's important to consult with a healthcare professional before combining St. John's Wort with other medications.

Common Side Effects to Watch For

When taken orally, common side effects of St. John's Wort may include diarrhea, dizziness, dry mouth, gastrointestinal discomfort, fatigue, headache, insomnia, restlessness, and sedation. When used topically, it may cause skin rash and increased sensitivity to sunlight, known as photodermatitis.

Are Supplements Standardized?

Yes, various St. John's Wort preparations used in clinical research are standardized to ensure consistent content of active components. The standardization is usually based on the concentration of hypericin or hyperforin. Different products may have varying standardizations, and some may also include additional ingredients in combination with St. John's Wort.

Drugs that interact with St. John's Wort